Magnetic fields of non-degenerate stars

TL;DR

This paper reviews the presence, detection, and properties of magnetic fields in non-degenerate stars across the HR diagram, discussing their origins and influence on stellar evolution.

Contribution

It provides a comprehensive overview of magnetic field characteristics, detection methods, and their implications in various types of non-degenerate stars and protostars.

Findings

Magnetic fields vary widely in strength and topology among non-degenerate stars.

Detection techniques include spectropolarimetry and Zeeman effect measurements.

Magnetic fields influence star formation, evolution, and end states.

Abstract

Magnetic fields are present in a wide variety of stars throughout the HR diagram and play a role at basically all evolutionary stages, from very-low-mass dwarfs to very massive stars, and from young star-forming molecular clouds and protostellar accretion discs to evolved giants/supergiants and magnetic white dwarfs/neutron stars. These fields range from a few microG (e.g., in molecular clouds) to TeraG and more (e.g., in magnetic neutron stars); in non-degenerate stars in particular, they feature large-scale topologies varying from simple nearly-axisymmetric dipoles to complex non-axsymmetric structures, and from mainly poloidal to mainly toroidal topology. After recalling the main techniques of detecting and modelling stellar magnetic fields, we review the existing properties of magnetic fields reported in cool, hot and young non-degenerate stars and protostars, and discuss our understanding of the origin of these fields and their impact on the birth and life of stars.